Statistical Occurrence and Distribution of High‐Amplitude Whistler Mode Waves in the Outer Radiation Belt

Abstract

Abstract We present the first statistical analysis with continuous data coverage and nonaveraged amplitudes of the prevalence and distribution of high‐amplitude (>5 mV/m) whistler mode waves in the outer radiation belt using 5 years of Van Allen Probes data. These waves are most common above L = 3.5 and between magnetic local time of 0–7 where they are present 1–4% of the time. During high geomagnetic activity, high‐amplitude whistler mode wave occurrence rises above 30% in some regions. During these active times the plasmasphere erodes to lower L and high‐amplitude waves are observed at all L outside of it, with the highest occurrence at low L (3.5–4) in the predawn sector. These results have important implications for modeling radiation belt particle interactions with chorus, as large‐amplitude waves interact nonlinearly with electrons. Results also may provide clues regarding the mechanisms which result in growth to large amplitudes.